Replace `fetch` requests to `xhr` in Cypress configuration

cypress.js

before(() => {
    Cypress.log({});

    cy.request('https://unpkg.com/unfetch@4.1.0/dist/unfetch.umd.js', {log: false}).as('unfetch').then(unfetch => {
        Cypress.on('window:before:load', win => {
            delete win.fetch;
            win.eval(unfetch);
            win.fetch = win.unfetch;
        });
    });
});